A pharmacist who described Islamic State fighters as “not bad people” has been convicted of showing a beheading video to a primary school pupil.

Zameer Ghumra “brainwashed” the child and his younger brother and told them they would have to decapitate people once they arrived in Syria, his trial heard.

Ghumra, 38, taught them how to survive a bomb attack and fight with knives, rewarding them with sweets to keep them onside.

He will be sentenced on Friday after being found guilty of disseminating “terrorist propaganda” in the form of a graphic Twitter video between January 2013 and September 2014.

The trial at Nottingham crown court heard how Ghumra followed various Isis-linked social media accounts and made the two unidentified children follow similar accounts.

Although he worked as a pharmacist in Oundle, Northamptonshire, Ghumra was said to have been setting up a madrasa, an Islamic religious school.

The jury was told how Ghumra had online conversations with Anjem Choudary, the jailed radical preacher, describing him as “a good man” to the children.

Giving evidence in court, one of the boys said Ghumra had shown him “a lot” of beheading videos. “He had Isis training videos and people being beheaded,” he said. “There was talking and then the American soldier was beheaded. It made me feel disgusting. He said: ‘If you truly love Allah then you do it.’ I told him I get a horrid feeling when I see this.”

The boy told the court: “He believes in a very, very, very extreme Islam. He believes if anyone’s non-Muslim and they say anything bad about Islam you kill them. And you can’t make friends with any non-Muslim.”

The boys’ mother told the court she had grown increasingly concerned about the man’s influence on the children, who she said were “waking up in the night because they think someone is killing them”.

She said: “My kids have been forced to watch Isis training videos. He told them: ‘We will have to do this one day.’ He told them all kafirs [non-believers] go to hell even if they’re good people.”

She claimed that one of her children had been shown a beheading video and was told by Ghumra: “We will have to do this when we go to Syria.” She added: “He said if you truly believe in God you do it for him. He said they would go to Turkey and make a run for it.”

The court heard that after Ghumra’s arrest at Birmingham airport in September 2015, a computer was seized showing 1,600 search results for terms including “survival knives” and “bushcraft”.

However, after police officers searched his home, neither the phone containing the beheading video nor the video itself was recovered.

Speaking afterwards, Sue Hemming, of the Crown Prosecution Service, said: “Zameer Ghumra tried to brainwash impressionable children with this violent ideology by making one watch beheading videos and urging them both to adopt a hardline religious outlook.

“The CPS case was that he intended to radicalise them in the hope that they would go on to be involved in terrorism.

“The children were brave to give evidence and we would like to thank them for helping to secure this conviction of a dangerous man.”